The research of this program concentrates on the structural aspects of the rod outer segment disk membrane of the bovine eye by means of X-ray diffraction. Knowledge of this structure is necessary for an understanding of how photon absorption leads to neural stimulation. Efforts to date have been subject to uncertainties because of the long time exposures required. Using the image intensification-computer controlled TV data acquisition and analysis techniques we have developed, we can obtain data in much shorter times than previously and analyze to determine the conformational changes upon bleaching, as well as some information about the orientation and extent of the protein in the disk. Our goals for the coming year include 1) Phase the high resolution data already obtained; 2) investigate the later rhodopsin intermediates by means of a synchrotron radiation experiment; 3) Measure the diamagnetic anisotropy of isolated disk membranes; 4) Examine the effects of peripheral disk proteins on the disk profiles; 5) Perform a neutron diffraction experiment to contrast enhanced rhodopsin; 6) Develop time resolved assays for disk peripheral protein attachment.